package com.xiayuanxing.arithmetic.Algorithm.BinarySearch;

/**
 * 二分查找法，非递归
 */
public class BinarySearchNoRecur {


    public static void main(String[] args) {

        int[] arr = {1,3,8,10,11,67,100};
        int index = binarySearch(arr,1007);
        System.out.println("下标："+index);

    }


    /**
     *二分查找的非递归实现
     * @param arr 待查找的数组，arr是升序
     * @param target 需要查找的数
     * @return 返回对应的下标，-1表示没有找到
     */
    public static int binarySearch(int[] arr, int target){
        int left = 0;
        int right = arr.length - 1;
        while(left <= right){
            //说明继续查找
            int mid = (left + right)/2;
            if (arr[mid] == target){
                return mid;
            }else if (arr[mid] > target){
                //需要向左边查找
                right = mid - 1;
            }else{
                //需要向右边查找
                left = mid + 1;
            }
        }
        return -1;
    }
}
